Therefore, we investigated the haemodynamic changes in primary and secondary hypertension and in the control subjects with non-invasive radial pulse wave analysis and whole-body impedance cardiography. The method includes the determination of volume status using bioimpedance spectroscopy, determination of peripheral and central BP, cardiac function, vascular resistance, arterial compliance and indices of pulse wave reflection. Besides the measurements performed in the supine position, passive orthostatic challenge is included in the protocol to assess the upright functional haemodynamic status.